I go to school, so I don't really have much wiggle room when it comes to making food..
I always keep chicken breasts, and ground beef in the freezer. I just them it out the day before I need it in the morning, and let it thaw out during the day, and cook it when I get back from class.
I also try to keep a re-sealable bags of veggies in my fridge for easy access.
I usually put stuff I just made in a ziploc bagX2 or in a plastic container, I don't like freezer burn. I really don't know how long it lasts, since I'm always going through food.
I carry quite a bit of food on me during school hours, along with 3 large bottles of water.
It's usualy chicken breast/lean burger on whole wheat with olive oil, spinach, tomato, and hummus. A ziploc bag of baby carrots, and almonds/deer jerky for a snack.
And later, two of these...(they also come in salmon, and unflavored and other flavors)
They are life savers, along with a bag of baby spinach.